Summary: Climate changes directly affect tree growth. Tree performance under changing conditions is maintained by xylem structure that determines the hydraulic and mechanical properties of a stem. The interest for the understanding of how trees grow during the climate change has led to the development of efficient methods for measuring and monitoring growth. Xylogenesis and annual radial increments of Norway spruce (Picea abies (L.) Karst.) in Trentino (Eastern Italian Alps) were monitored between 2010 and 2012 with automatic dendrometers and cell analysis. The analyses of intra-annual dynamics of wood formation were used to describe seasonal changes in xylem differentiation phases and to calculate the timing of cell development in Norway spruce. The investigation was conducted in two sites at different elevation, Savignano (650 m a.s.l.) and Lavazè (1800 m a.s.l.), to detect the effect of climate signals in the day-to-day dynamics of wood formation. Dendroclimatological analysis was performed to examine the relationship between the formation of tree rings of Norway spruce and climatic parameters in two contrasting sites. Climate–growth relationships were analyzed using correlation function analysis and moving correlation function, detecting relations between phenological phases of wood formation and seasonal patterns of temperature and precipitation. Effects of climatic variables on stem diameter variation and cell structure were examined, respectively, daily and each 15 days .The results were interpreted according to the dynamics of forest vegetation and synchronicity of cambial activity with meteorological parameters. Models of cambial and tree growth are required to improve the predictive power of ecosystem process models, in which tree growth is often an essential and complex component.